When intricate items, such as jewelry, have to be duplicated in mass production, the pattern or model is enclosed in a rubber-like plastic mold which is very resilient and strong. Then to remove the model which is imbedded in the mold, formed around the model, the mold has to be split preferably into two sections which are left joined together along one edge so that the two sections can be replaced alongside each other to reform the cavity which the model occupied. Now the cavity may be filled with a "wax" which, when hardened, takes the shape of the cavity. The wax formed is removed to be used in forming a ceramic mold so that the metallic jewelry can be cast using the well known "lost wax casting process." Since the rubber mold is very soft and resilient up to now one found it very difficult to anchor this mold when one attempts to split it with a sharp knife.